A gas turbine engine includes a turbomachinery core having a high pressure compressor, combustor, and high pressure turbine (“HPT”) in serial flow relationship. The core is operable in a known manner to generate a primary gas flow. The high pressure turbine includes annular arrays (“rows”) of stationary vanes or nozzles that direct the gases exiting the combustor into rotating blades or buckets. Collectively one row of nozzles and one row of blades make up a “stage”. Typically two or more stages are used in serial flow relationship. These components operate in an extremely high temperature environment, and must be cooled by air flow to ensure adequate service life.
Due to operating temperatures within the primary flowpath of the gas turbine engine, it may be beneficial to utilize materials that are high temperature capable. For example, to operate effectively in such strenuous temperature and pressure conditions, composite materials have been suggested and, in particular for example, ceramic matrix composite (CMC) materials. These materials have higher temperature capability than metallic parts. The higher operating temperatures within the engine result in higher engine efficiency if cooling air for parts can be reduced, and these materials may be lighter weight than traditionally used metals. CMC, for example, may require less cooling air. However, such CMC and other materials have mechanical properties that must be considered during the design and application of the CMC. CMC materials have relatively low tensile ductility or low strain to failure when compared to metallic materials. Also, CMC materials have a coefficient of thermal expansion which differs significantly from metal alloys used as restraining supports or hangers for CMC type materials.
One use for such materials is in a turbine shroud. However, various problems are known to exist with shroud hanger assemblies. For example, some assemblies utilize a one-piece hanger construction that is deflected apart during the insertion of the shroud into a cavity of the shroud hanger. This interference at assembly is required because of the difference in coefficient of expansion of the hanger and shroud. However, this mechanical deflection may cause bending or even yielding of the hanger arms during positioning of the shroud which is undesirable and may cause premature deformation and leakage at high temperature. Therefore, it may be beneficial to have an assembly which is more easily assembled and will not cause yielding of the hanger.
As stated, the shroud hanger assembly must be properly sealed. Such sealing issues develop due to thermal growth of parts of differing materials. Such growth may result in gaps between sealing surfaces and may be undesirable.
It may be beneficial to overcome these and other deficiencies to provide a shroud hanger assembly which provides for sealing of the interfaces between parts of differing material and minimizes the required deflection at assembly required to compensate for differential thermal growth therebetween.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the invention is to be bound.